This invention relates to restraint systems for vehicle occupants and in particular to restraint systems which automatically inflate upon impact or collision.
Naval aviators normally wear a restraint during flight which is basically a lap belt and shoulder harness attached to a seat. During a crash the current restraint system may not be fully effective for the following reasons.
The restraint system may not have been completely tightened by the crewman when initially placed on and if worn loosely will allow a downward and forward motion of the crewman into his restraint during a crash. This motion results in the crewman experiencing high decelerative and strap loads as his velocity decreases to the velocity of the seat.
Depending on the severity of the crash, serious injury or death may result from the transfer of kinetic energy between the crewman and the restraint system. Under high crash forces, the crewman moves into his restraint, loading the straps to thousands of pounds. This load must be reacted by that part of his anatomy directly covered by the straps whose width is normally less than two inches. If the load applied to an anatomic structure exceeds its limit then that structure will fracture resulting in injury to the crewman.
The conventional restraint has been designed to limit torso motion. During a crash the upper torso is abruptly stopped in its forward motion as it loads the straps; however, the crewman's head and neck hyperflex and rotate violently forward until arrested by muscular involvement or by direct contact of the mandible and sternum. Serious injury or death may result from this forward whiplash motion. Although the exact mechanism causing injury is not well understood it is known that if the head is supported and restrained from whipping, the probability of injury will be reduced.